function GoGoGo(objName)
{
var img=document.getElementById(objName) ;
img.style.position="absolute";
img.style.left=parseInt(window.screen.availWidth*Math.random()) + "px";
img.style.top=parseInt(window.screen.availHeight*Math.random()) + "px";
img.setAttribute("xDir",1);
img.setAttribute("yDir",1);
window.setInterval("randPosition(" + objName + ")","10","JavaScript");
}

function randPosition(obj)
{
var x=parseInt(obj.style.left);
if(x>=window.screen.availWidth-obj.width-20)
obj.setAttribute("xDir",-1);
if(x<=0)
obj.setAttribute("xDir",1);
x+=parseInt(obj.getAttribute("xDir"));
var y=parseInt(obj.style.top);
if(y>=window.screen.availHeight-obj.height-100)
obj.setAttribute("yDir",-1);
if(y<=0)
obj.setAttribute("yDir",1);
y+=parseInt(obj.getAttribute("yDir"));
 
obj.style.left=x +"px";
obj.style.top =y +"px";

}
